Writable and printable colloidal gold solution

Abstract

The present invention relates to an aqueous colloidal gold solution, comprising (a) nano-particular gold particles, (b) a compound having a polar tertiary amino group conjugated via a hydrophobic aromatic residue with a weaker alkaline group, and (c) a stabilizer comprising a mercapto group (—SH) and an acidic group, in particular a sulfonic acid group (—SO 3 − ). This gold solution uses an ecologically compatible medium and is suited in an especial manner for writing and for printing, also for inkjet printers, since it has a long-term storage life and generates an attractive metal-like gold sheen.

1. An aqueous colloidal gold solution comprising an aqueous medium and
 (a) gold particles in colloidal form, 
 (b) a compound having a polar tertiary amino group conjugated via a hydrophobic aromatic residue with a weaker alkaline group which can also be a part of the aromatic residue, and 
 (c) a stabilizer comprising a mercapto group (—SH) and an acidic group, 
 wherein said solution has a gold content of 8 to 10% by weight. 
 
     
     
       2. An aqueous colloidal gold solution according to  claim 1 , wherein the colloidal gold particles have an average diameter of 1 to 20 nm. 
     
     
       3. An aqueous colloidal gold solution according to  claim 1  or  2 , wherein the aromatic residue of the compound (b) is a N-heteroaromatic residue with the nitrogen atom as weaker alkaline group. 
     
     
       4. An aqueous colloidal gold solution according to  claim 3 , wherein the heteroaromatic residue is a pyridine residue. 
     
     
       5. An aqueous colloidal gold solution according to  claim 4 , wherein the compound (b) is 4-dimethylamino-pyridine (DMAP). 
     
     
       6. An aqueous colloidal gold solution according to  claim 1 , wherein the stabilizer (c) comprises a sulfonic acid group (—SO 3   − ). 
     
     
       7. An aqueous colloidal gold solution according to  claim 6 , wherein the stabilizer (c) is a mercapto-(C 1−5 )-alkylsulfonic acid salt. 
     
     
       8. An aqueous colloidal gold solution according to  claim 7 , wherein the stabilizer (c) is a 2-mercaptoethane sulfonic acid salt. 
     
     
       9. An aqueous colloidal gold solution according to  claim 1 , comprising furthermore, as evaporation blocker,
 (d) a polar organic compound with a vicinal dihydroxy group or an oligomer thereof. 
 
     
     
       10. An aqueous colloidal gold solution according to  claim 9 , wherein the compound (d) is ethylene glycol. 
     
     
       11. An aqueous colloidal gold solution according to  claim 1 , having the following composition:
 (a) 8 to 10% by weight of the gold nanoparticles, 
 (b) 0.1 to 3% by weight of the compound having a tertiary amino group, 
 (c) 0.2 to 0.6% by weight of the stabilizer, and optionally 
 (d) 1 to 8% by weight of the evaporation blocker, each based on the total weight of the aqeous compostion. 
 
     
     
       12. An aqueous colloidal gold solution according to  claim 1 , having a pH of 8 to 11. 
     
     
       13. Ink or printer cartridges containing the aqueous colloidal gold solution of  claim 1 . 
     
     
       14. Printer cartridge according to  claim 13 , which is an ink jet printer cartridge. 
     
     
       15. An aqueous colloidal gold solution according to  claim 6 , comprising furthermore, as evaporation blocker,
 (e) a polar organic compound with a vicinal dihydroxy group or an oligomer thereof. 
 
     
     
       16. Ink or printer cartridges containing the aqueous colloidal gold solution of  claim 6 . 
     
     
       17. Ink or printer cartridges containing the aqueous colloidal gold solution of  claim 11 .